二连盆地古地貌特征及其对砂岩型铀矿的制约  

The Paleogeomorphology Feature of Erlian Basin and Its Constrains on Sandstone-type Uranium Deposits

作　　者：刘持恒 刘武生[1] 史清平[1] 张文东 张梓楠[1] LIU Chiheng;LIU Wusheng;SHI Qingping;ZHANG Wendong;ZHANG Zinan(CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]核工业北京地质研究院,中核集团铀资源勘查与评价技术重点实验室,北京100029

出　　处：《铀矿地质》2020年第5期346-353,共8页Uranium Geology

基　　金：中核集团龙灿工程(二期)科研项目“二连基地砂岩型铀成矿环境和条件调查评价研究”(编号:地LCEQ01)资助。

摘　　要：二连盆地赛汉组上段是重要的产铀层位,其沉积环境和地层分布特征通常受到古地貌控制明显,因此开展二连盆地赛汉期末的古地貌恢复工作有助于多方位认识盆地在该时期中的沉积格局及其对砂岩型铀成矿的制约。通过将二连盆地乌兰察布坳陷和马尼特坳陷875口钻井资料按岩性进行逐层回剥和去压实校正编制了研究区赛汉期末的古地貌图。定量的地貌分析表明,二连盆地赛汉期末古地貌为宽阔的低坡度河谷地貌区,进一步可划分为平原、微斜坡和缓斜坡地貌单元。通过与前人在该区绘制的沉积相图对比研究发现,古地貌坡折带是控制河道亚相分布的关键。宽阔的河谷为河床侧向迁移提供了空间,有利于形成大范围连片的河道砂体,提供更多的铀储层空间。河床两侧的微斜坡-缓斜坡有利于形成倾斜的空间形态,有利于形成宽阔的氧化还原铀成矿带。古地貌坡折带很有可能为铀矿体富集的关键部位。The Upper Member of Saihan Formation in Erlian Basin is an important layer for uranium deposits.Because the sedimentary environment and distribution characteristics are controlled by the basin paleogeomorphology,therefore,restoring the paleogeomorphology of Erlian Basin at the end of the Saihan Age will help us to understand the sedimentary pattern and influencl on the sandstone-type uranium deposits.In this paper,the paleogeomorphology map at the end of the Saihan Age was finished by stripping back the sedimentary depth in 875 boreholes.In detail,the stripping back analysis was conducted layer by layer according to the lithology with the decompaction calibration.Furthermore,quantitative geomorphology analysis showed that the paleogeomorphology of the Erlian Basin at the end of the Saihan Age was a wide and low-slope river valley,which can be further divided into plain,micro-slope and gentle slope.Compared to the previous sedimentary face map,the slope break zone of paleogeomorphology is the key to control the distribution of river channel of Wulanchabu and Manite depression.In addition,the wide river valley provided space for lateral migration of riverbed,which was conducive to generate a wide range of contiguous channel sand bodies and provided more space for uranium reservoirs,the micro-slope and gentle slope on both sides of the riverbed constituted an inclined spatial morphology,which can promote the formation of a wide oxidation-reduction uranium metallogenic belt.Finally,we concluded that the slope break zone could be a key position to enrich uranium ore body.

关 键 词：古地貌 二连盆地 砂岩型铀矿 古河道 

分 类 号：P619.14[天文地球—矿床学]